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A&P Lect.
Chapter 4 Genetics and Cellular Function
| Mendelian genetics | correlation between chromosome behavior and the laws of heredity |
| deoxyribonucleic acid (DNA) | a long threadlike molecule with uniform diameter but varied length |
| total length of DNA | 2 meters |
| how many molecules in nucleus of most human cells | 46 |
| genes | genetic instructions for synthesis of proteins |
| gene | segment of DNA that codes for specific protein |
| genome | all the genes of one person; all the DNA in one 23 chromosome set |
| genes are... | turned on and off from day to to day, hour to hour |
| are the products of genes always needed? | no |
| can genes be permanently turned off? | yes |
| example of when genes can be turned off | genes for hemoglobin or digestive enzymes |
| gene expression | DNA (transcription) ->RNA (translation-> protein |
| homo sapiens have ... previously believed | fewer genes than the 100,000 |
| genes generate.. | millions of different proteins |
| genes average.. | about 3,000 bases long |
| all humans are atleast.. | 99.99% genetically identical |
| we now know the locations of ... | 1400 disease producing mutations |
| genomic medicine | new branch of medical diagnosis and treatment |
| sister chromatid | 2 parallel filaments of identical DNA (within each chromosome) |
| final compaction | enables 2 sister chromatids to be pulled apart and carried to separate daughter cells without damage to DNA |
| centromere | where chromasomes |
| nucleotide | consists of a sugar, a phosphate group, and a single- or double-ringed nitrogenous base |
| base C and T | cytosine & thymine have single carbon nitrogen ring and classified as pyrimidines |
| base A and G | Adenine & guanine have double carbon nitrogen rings and classified as purines |
| discovered double helix | James Watson and Francis Crick |
| what happened in the disocvery of double helix DNA | Rosalin Franklin and Maurice Wilkin were working on x-ray photographs that Wilkins ended up showing Watson and Crick and they won recognition but nobel prize was shared between the three minue Franklin because she had dies, probably due to the xrays |
| how many nucleotide pairs in a human genome? | 3.1 billion |
| describe structure of chromosomes | there are 46 human chromosomes that come in 2 sets of 23. one set from each parent. each pair of chromosomes has same genes but different alleles |
| chromatin | proteins to form a fine filamentous material |
| DNA replication | vefore a cell divides it duplicates its DNA so it can give a complete copy of all its genes to each daughter cell |
| kintochore | protein plaques on either side of the centromere |
| cell cycle | cell's life cycle that extends from one division to the next ; G1,S, G2,M,Cytokinesis |
| G1 phase | the first gap phase: interval between cell division and DNA replication, accumulates materials needed to replicate DNA |
| S Phase | synthesis phase: DNA replication occurs |
| G2 Phase | second gap phase interval between DNA replication and cell division, synthesizes enzymes that control cell division, repairs DNA replication errors |
| M Phase | miotic phase: cell replicates its nucleus |
| interphase | collection of G1 S and G2 phases |
| G0 (zero) | cells that have left the cycle for a "rest"- muscle, nerve cells |
| mitosis | cell division in all body cells except the eggs and sperm |
| functions of mitosis | -development of the individual from one fertilized egg to some 40 trillion cells -growth of all tissues and organs after birth -replacement of cells that die -repair of damaged tissues |
| 4 phases of mitosis | prophase, metaphase, anaphase, telophase |
| cytokinesis | the division of cytoplasm into 2 cells telophase is the end of the nuclear division but overlaps cytokenesis pinches in 2 to form new daughehter cells creates cleavage furrow around the equator of cell |
| how is cytokinesis achieved | -achieved by motor protein myosin pulling on microfilaments of actin in the terminal web of cytoskeleton |
| when do cells divide | when they have enough cytoplasm for 2 daughter cells -they have replicated their DNA -they have adequate supply of nutrients -they are stimulated by growth factor -when neighboring cells die, opening up space in a tissue to be occupied by new cells |
| growth factor | signals secreted by blood platelets, kidney cells, and other sources |
| when do cells stop dividing | - when nutrients or growth factors are withdrawn -when they snugly contact neighboring cells -when they undergo contact inhibition |
| contact inhibition | the cessation of cell division in response to contact with other cells |
| Meiosis | -cell division in eggs and sperm |
| heredity | transmission of genetic characteristics from parent to offspring |
| karyotype | chart of 46 chromosomes laid out in order by size and other physical features |
| homologous chromosomes | 23 pairs: the 2 members of each pairs |
| autosomes | 22 pairs that look and carry versions of the same genes |
| chromosomes in homologous chromosomes | 1 chromosome from each pair inherited from each parent |
| sex chromosomes | X & Y |
| female chromosome | homologous pair of X chromosomes |
| male chromosome | has 1 X and one much smaller Y chromosome |
| diploid | any cell with 23 pairs of chromosomes (somatic cells) |
| haploid | contain half as many chromosomes as somatic cells: sperm and egg cells (germ cells) |
| fertilization | restores diploid number to the fertilized egg and the somatic cells arise from its |
| locus | the location of a particular gene on a chromosome |
| alleles | different forms of gene at same locus on 2 homologous chromosomes |
| dominant alleleous | (represented by capital letter) -corresponding trait is usually detectable in the individual -masks the effect of any recessive allele that may be present -produces protein responsible for visible trait |
| recessive allele | (represented by lower case) -expressed only when present on both of the homologous chromosomes - no dominant alleles at that locus |
| genotype | the alleles that an individual possesses for a particular trait |
| homozygous alleles | 2 identical alleles for a trait |
| heterozygous alleles | different alleles for that gene are also carriers for hereditary diseases such as cystic fibrosis |
| phenotype | an observable trait |
| expressed allele | an allele is expressed if it shows in the phenotype of an individual |
| punnet square | shows how 2 heterozygous parents with cleft chins have child with uncleft chin |
| gene pool | collective genetic makeup of population as a whole |
| multiple alleles | more than 2 allelic forms of a trait -100 alleles are responsible for cystic fibrosis -3 alleles for ABO blood types |
| codominant | bot alleles are equally dominant -type AB blood -both are phentypically expressed |
| incomplete dominance | phenotype intermediate between traits each allele would have produced alone |
| polygenic inheritance | genes at 2 or more loci, or even chromosomes,contribute to a single phenotypic trait such as skin and eye color, alcoholism, mental illness, cancer, and heart disease |
| pleiotropy | one gene produces multiple phenotypic effects |
| alkaptonuria | mutation on chromosome 3 that blocks the breakdown of tyrosine |
| sickle cell disease | example of pleiotropy |
| sex linked traits | carried on the X and Y chromosomes and therefore tend to be inherited by one sex more than the other recessive color blindness allele on X, no gene locus for that trait on Y, so red-green color blindness more common in men (mother is the carrier) |
| mutations | changes in DNA structure due to replication errors or environmental factors (radiation, viruses, chemicals) |
| mutations: good/bad | some mutations cause no illness effects others kill the cell, turn it cancerous, or cause genetic defects in future generations |
| benign tumor | slow growth; contained in fibrous capsule; will not metastasize; usually easy to treat |
| malignant tumor | called cancer; fast growing metastize |
| metastisize | give off cells that seed the growth of multiple tumors elsewhere |
| oncology | medical specialty that deals with both benign and maligant tumors |
| tumor angiognesis | in-growth of blood vessels stimulated by energy-hungry tumors |
| how are cancers named | for tissue of origin |
| cancer names | carcinomas: in epithelial tissue lymphomas: in lymph nodes melanomas: in pigment cells of dermis (melanicytes) leukemias: in blood-forming tissues sacromas: in bone, other connective tissue, or muscle |
| carcinogens | environmental cancer-causing agents that trigger gene mutations |
| what are some carcinogens | radiation: ultraviolet rays, Xrays chemical: cigarette tar, food preservatives, industrial chemicals viruses: human papilomavirus, hepatitis c, type 2 herpes simplex |
| cancers hereditary? | only 5-10% |
| oncogenes | cause cell division to accelerate out of control -excessive production of growth factors that stimulate mitosis - the production of excessive growth-factor receptors |
| tumor-suppressor genes | inhibit development of cancer -oppose action of oncogenes -some trigger DNA-repair enzymes |
| effects of cancer | -replace functional tissue in vital organs -steal nutrients from the rest of the body -weaken ones immunity -open the door for opportunistic infections -often invade blood vessels, lung tissue, or brain tissue |
| cachexia | sever wasting away of depleted tissues |
| mitosis | nuclear division; cell division of somatic cells |
| prophase | chromosomes condense and nuclear envelope breaks down. spindle fibers grow from centrioles. centrioles migrate to opposite poles of cell |
| metaphase | chromosomes lie along midline of cell. some spindle fibers attach to kinetochores. fibers of aster attach to plasma membrane |
| anaphase | centromeres divide in two. spindle fibers pull sister chromatids to opposite poles of cell. each pole now has an identical set of genes |
| telophase | chromosomes gather at each pole of cell. Chromatin decondenses. new nuclear envelope appeaars at each pole, new nucleoli appear in each nucleus. mitotic spindle vanishes |
Created by:
sg109
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